screwfitmentdatabase

How to buy the right screws online

Nearly every wrong-screw order comes down to three details that listings bury: the head shape, the exact length, and whether the thread is metric or a US size that looks metric.

Decode the listing title

A full title reads something like 'M3 x 6 mm A2 stainless pan head Phillips machine screw'. That is size, length, material, head shape, drive and type.

If any of those five is missing, assume the worst case. 'M3 screws, 100 pack' tells you nothing about length or head.

Are assortment kits worth it?

For general repairs, yes — a sorted metric box covering M1.6 to M3 in several lengths pays for itself the first time you avoid a shipping wait.

For a specific repair, no. Buy the exact size; kit screws are often soft, and a soft screw strips before it tightens.

Signs of a bad batch

  • The drive recess looks shallow or rounded before you have used it.
  • Lengths vary visibly within the same bag.
  • 'Stainless' with no grade stated — no A2 or A4 marking.
  • A price far below everyone else for a large count.

Order a size range, not one length

Lengths are cheap. If you are not certain, buy the length you think you need plus the one either side. It costs less than a second delivery and far less than a screw pushed through a board.

Common questions

How many screws should I buy?

More than you need. Tiny screws get lost, and the postage usually costs more than the extra screws.

What does A2-70 mean?

A2 is the stainless grade (304-type) and 70 is the strength class, meaning 700 MPa tensile. It is the normal quality for general stainless screws.

Are branded screws worth the extra?

For anything you will tighten hard or reuse, yes — the drive recess is cut properly, so bits do not slip and heads do not round.

Keep reading

How to measure a screw and work out its metric sizeRemoving a stripped tiny screw without wrecking the deviceLaptop screw sizes explainedMetric vs imperial screws — the sizes that fool everyoneThread locker and torque on small screwsScrew head shapes and when each one is rightPutting screws into plastic without stripping itChoosing the right screw lengthWhich screw material to use, and what rustsSecurity screws and how to get them outKeeping track of tiny screws during a repairCross-threaded, seized and spinning screwsWashers, locking methods and screws that will not stay tightOpening a laptop, phone or console without damageScrew standards: ISO, DIN, ANSI and JISIdentifying a screw when the manufacturer never published the sizeChoosing and fitting screws in 3D printed partsEyeglass, watch and hearing aid screwsLicense plate, trim and small automotive screwsAll tools

Tools and screws for this job

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